• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.459-465
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• 1999

This work focused on the effects of the timing and the frequency of shoot cutting to maximize the productivity and the nutrient removal of three emergent macrophytes, Phragmites communis, Zizania latifolia and Typha angustifolia in natural wetlands. Shoot cutting significantly enhanced biomass production and resulted in more nitrogen and phosphorus removal from water in these three experimental species, compared to those of control. However, the frequency and the timing of shoot cutting, and the enhancement ratio were different among three species. For Phragmites stands, the highest productivity was 1.9 times of control in June treatment of the first year experiment, while 1.3 times in May treatment of the second year experiment. Zizania and Typha stands were both 1.2 times of control in August treatment and June and August treatment. Calculating the total annual removal rate of nitrogen and phosphorus based on the highest productivities among treatments, in Phragmites stands, 2.0 times of nitrogen and 1.8 times of phosphorus were removed in the first year, and both 1.4 times in the second year experiment. Likewise, for nitrogen and phosphorus; 2.4 and L.8 times in Zizania stands, and 1.8 and 1.9 times in Typha stands were removed. Overall, these results suggested that cutting treatment of shoots be effective. Thus, shoot cutting of two times during a growing season were recommended to maximize the effects: that is, in May or June, and October for Phragmites stands, and in August and October fur Zizania and Typha stands.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.478-488
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• 2017

Stormwater filtration is widely used for the urban runoff treatment. However, intensive maintenance and lack of information about the performance have resulted in an increased need of proper evaluation. In this study, the performance of an upflow stormwater runoff filtration system, consisting of a supporting unit and a filtration unit filled with a ceramic media, was investigated. The maximum head loss increase was about 3 cm under the suspended solid (SS) load of $30kg/m^2$ and the SS removal was more than 96%, when the filtration velocity was 20-40 m/h. The head loss and the porosity of the media can successfully be described by a power model. It was confirmed that the a significant amount of SS can effectively be removed at supporting unit, minimizing SS load to the filter media bed. Several backwashing strategies have been tested to establish the optimum condition. It was found that the stagnant water discharge is important to minimize the SS release immediately after backwashing. Also, the filter bed loaded with $400-450kg/m^2$ SS can almost completely be washed to reduce the head loss to the that of empty bed. The results in this study indicate that the upflow ceramic media filter is an excellent alternative to stormwater treatment, with high SS removal and long lifespan.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.239-246
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• 2012

This study was performed to investigate the removal characteristics and mechanism of heavy metals using pellet-type ceramics(ZS ceramics), in which natural zeolite was mixed and calcined with converter slag. The optimal calcination temperature range was measured to be $600{\sim}800^{\circ}C$. The calcination time had little effect on the removal of heavy metal in acid wastewater. The adequate dose of ceramics was shown to be 2~5% for removal of heavy metals in acid wastewater. The maximum removal capacity of ZS ceramics for heavy metals were observed to be Al 84.7 mg/g, Cd 37.3 mg/g, Cr 81.7 mg/g, Cu 55.6 mg/g, Fe 57.2 mg/g, Mn 32.1 mg/g, Ni 38.0 mg/g, Pb 71.6 mg/g, Zn 46.3 mg/g. The pH played a pivotal role in the removal of heavy metals by ZS ceramics. The analysis results of mechanism exhibited that the ZS ceramics could act as a multi-functional ceramics for removal of heavy metals in acid wastewater by adsorption, ion-exchange, or precipitation.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.729-734
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• 2008

The higher valence state of iron i.e., Fe(VI) was employed for the treatment of Cu(II)-EDTA in the aqueous/waste waters. The ferrate(VI) was prepared through wet oxidation of Fe(III) by sodium hypochlorite. The purity of prepared Fe(VI) was above 93%. The stability of Fe(VI) solution decreased as solution pH decreased through self decomposition. The reduction of Fe(VI) was obtained by using the UV-Visible measurements. The dissociation of Cu(II)-EDTA complex through oxidation of EDTA using Fe(VI) and subsequent treatment of organic matter and metal ions by Fe(III) reduced from Fe(VI) in bench-scale of continuous flow reactor were studied. The removal efficiencies of copper were 69% and 79% in pH control basin and reactor, respectively, at 120 minutes as retention time. In addition, Cu(II)-EDTA in the reactor was decomplexated more than 80% after 120 minutes as retention time. From this work, a continuous treatment process for the wastewater containing metal and EDTA by employing Fe(VI) as muluti-functional agent was developed.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.438-443
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• 2007

This study was done to investigate perchlorate contamination in Nakdong river. The perchlorate was detected in Nakdong river and ranged from ND to $82.1{\mu}g/L$. The highest concentration was observed in Wheguan. The perchlorate concentration was decreased with the down stream of Nakdong river. Three different virgin activated carbons made of each coal(Calgon), coconut(Samchully) and wood(Picabiol) based activated carbon(AC) were tested for an adsorption performance of perchlorate in a continuous adsorption column. Breakthrough behavior was investigated that the breakthrough points of coal, coconut and wood based AC as 2,300 bed volumn(BV), 719 BV and 288 BV respectively. Adsorption capacity(X/M) of real, coconut and wood based AC was observed. The experimental results of adsorption capacity showed that coal based AC was highest$(768.2{\mu}g/g)$, coconut based AC was intermediate$(299{\mu}g/g)$ and wood based AC was lowest$(99.2{\mu}g/g)$. Moreover, carbon usage rates(CURs) for coal, coconut and wood based AC had been shown as 0.71 g/day, 2.16 g/day and 3.45 g/day respectively. The constant characteristic of the system, k of coal, coconut and wood based ACs were found to be 307.2, 102.5 and 94.2, respectively.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.83-88
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• 1998

Heavy metal removal by Z. ramigera 115 and soluble slime polymer producing mutant Z. ramigera 115SLR was investigated. Both strains showed similar tolerance against $Cd^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Ni^{2+}$ and $Fe^{2+}$. When cells were cultivated in the presence of 500 ppm $Cd^{2+}$, the mutant strain removed 1.5 fold more metal than the wild type did at same biomass. Metal adsorption capacities were in the order of Z. ramigera l15SLR polymer > Z. ramigera 115 polymer > Z. ramigera 115 cell >Z. ramigera l15SLR cell. The optimum pH for metal adsorption was 7.5. Langmuir and Freundlich isotherms indicated that Qmax and 1/n of Z. ramigera l15SLR polymer were 164.2 mg $Cd^{2+}$/g dw and 0.496, respectively. These results showed that the polymer of Z. ramigera l15SLR could be used as an effective metal adsorbate.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.306-312
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• 2006

Disposal of food garbage in most large cities is very troublesome task. To date, microbiological treatment has been received an attention as a garbage decomposition process. In this study, the inoculation effect of some cellulase, amylase and protease-producing bacteria and photosynthetic bacteria on food garbage treatment was examined. They were added into a treatment reactor specially designed in this study together with food garbage and incubated in various conditions for 15 days and the removals of food garbage and foul smell produced during the treatment were analyzed. Average decomposition percentages of the inoculated food garbage in treatment reactor were 11 and 18.8% under intermittent aeration (once in a day) and continuous aeration conditions (2 L/min), respectively, and these were higher than removal percentages in the corresponding uninoculated reactors,3.4 and 13.8%. Optimal pH and temperature for food garbage decomposition by inoculated bacteria were pH 7.0 and $30^{\circ}C$. Maximal decomposition percentage in the inoculated food garbage was 35% under the optimal condition (pH 7, $30^{\circ}C$, and continuous aeration). The malodor compounds generated from food garbage treatment such as complex foul smell and sulfur compounds were effectively reduced about 84% and 25.5%, respectively, with a biofilter composed of purple nonsulfur bacteria trapped in sponge. This decomposing capability of food garbage by these bacteria can be utilized for the rapid and efficient treatment of food garbage.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.697-703
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• 2005

Iron-coated sand(ICS) was prepared with variation of particle size of Joomoonjin sand, primary and secondary coating temperature, coating time, and dosage of initial Fe(III). An optimum condition of the preparation ICS was selected from the coating efficiency, stability of coated Fe(III), and removal efficiency of As(V). Coated amount of Fe(III) increased as primary coating temperature increased with smaller particle size of sand. Coating efficiency was quite similar over the investigated secondary coating temperature and time, while adsorption efficiency of As(V) onto ICS was severely reduced with ICS prepared at higher secondary coating temperature. By considering these results, an optimum secondary coating temperature and time for the preparation of ICS was selected as $150^{\circ}C$ and 1-hr, respectively. Coating efficiency increased us the dosage of initial Fe(III) up to 0.8 Fe(III) mol/kg sand and then no distinct increase was noted. Maximum As(V) adsorption was observed at 0.8 Fe(III) mol/kg sand. Secondary coating temperature and time were important parameters affecting stability of ICS, showing decreased dissolution of Fe(III) from ICS prepared at higher coating temperature and at longer coating time. From anionic type adsorption of As(V) onto ICS, it is possible to suggest the application of ICS for the removal of As(V) contaminated in acidic water system.

• The Korean Journal of Food And Nutrition
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• v.25 no.1
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• pp.26-31
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• 2012

For the purpose of production of GABA-rich tomato paste, this study was carried out to investigate GABA producing lactic acid bacteria from Korean traditional fermented food, Kimchi and optimize the culture conditions. As a result of fermentation, Lactobacillus brevis B3-20 among lactic acid bacteria isolated at the pre-experiments was the best producer of GABA at the tomato paste medium with 50%(wet-base) levels of dionized water. At the result of fermentation on the tomato paste medium with 0.5%(w/w) yeast extract, as a source of nitrogen, 3%(w/w) MSG(monosodium glutamate) and dionized water(the ratio of tomato paste and water was 2:8), Lb. brevis B3-20 produced the maximum GABA concentration, 143.38 mM. GABA-rich tomato paste showed the activity of free radical scavenging. Because GABA-rich tomato paste have functional ingredients such as ascorbic acid, lycopene, carotenoid, as well as GABA by lactic acid bacteria fermentation, GABA-rich tomato paste can be considered high functional materials.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.87-97
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• 2018

The cesium (Cs) removal from the contaminated water system has been considered to be difficult because the cesium likes to exist as soluble phases such as ion and complexes than the solid in water system. Many researches have focused on developing the breakthrough adsorbent to increase the cesium removal efficiency in water. In this study, the laboratory scale experiments were performed to investigate the feasibility of the adsorption process using the bamboo charcoal for the Cs contaminated water system. The Cs removal efficiency of the bamboo charcoal were measured and the optimal adsorption conditions were determined by the adsorption batch experiments. Total 5 types of commercialized bamboo charcoals in Korea were used to identify their surface properties from SEM-EDS and XRD analyses and 3 types of bamboo charcoals having large specific surface areas were used for the adsorption batch experiment. The batch experiments to calculate the Cs removal efficiency were performed at conditions of various Cs concentration (0.01 - 10 mg/L), pH (3 - 11), temperature ($5-30^{\circ}C$), and adsorption time (10 - 120 min.). Experimental results were fitted to the Langmuir adsorption isotherm curve and their adsorption constants were determined to understand the adsorption properties of bamboo charcoal for Cs contaminated water system. From results of SEM-EDS analyses, the surfaces of bamboo charcoal particles were composed of typical fiber structures having various pores and dense lamella structures in supporting major adsorption spaces for Cs. From results of adsorption batch experiments, the Cs-133 removal efficiency of C type bamboo charcoal was the highest among those of 3 bamboo charcoal types and it was higher than 75 % (maximum of 82 %) even when the initial Cs concentration in water was lower than 1.0 mg/L, suggesting that the adsorption process using the bamboo charcoal has a great potential to remove Cs from the genuine Cs contaminated water, of which Cs concentration is low (< 1.0 mg/L) in general. The high Cs removal efficiency of bamboo charcoal was maintained in a relatively wide range of temperatures and pHs, supporting that the usage of the bamboo charcoal is feasible for various types of water. Experimental results were similar to the Langmuir adsorption model and the maximum amount of Cs adsorption (qm:mg/g) was 63.4 mg/g, which was higher than those of commercialized adsorbents used in previous studies. The surface coverage (${\theta}$) of bamboo charcoal was also maintained in low when the Cs concentration in water was < 1.0 mg/L, investigating that the Cs contaminated water can be remediated up with a small amount of bamboo charcoal.